1. Field of the Invention
The present invention relates to a communication device having a radio unit for performing radio communication.
2. Description of the Related Art
There is a conventional communication device in which radio communication is established between a transmitter/receiver for performing speech communication and a communication device.
For example, there are facsimile devices similar to the above communication device. The facsimile device will be described below.
This facsimile device has a radio unit for performing radio communication with a transmitter/receiver, and a controller of the facsimile device controls the facsimile device and the radio unit. The controller controls the radio unit by a signal system inherent in the controller.
In a facsimile device in which radio communication is established between a transmitter/receiver and the facsimile device, when the transmitter/receiver receives an incoming notification to respond to the incoming notification, and the facsimile device performs an automatic receiving operation (so-called facsimile/telephone switching operation), a radio line between the transmitter/receiver and the facsimile device is suddenly cut off, or no notification is transmitted from the facsimile device to the transmitter/receiver even if the radio line is not cut off.
When communication between the transmitter/receiver and the facsimile device cannot be established due to radio wave jamming between the transmitter/receiver and the facsimile device, the transmitter/receiver outputs an alarm tone by an alarming unit built in the transmitter/receiver.
However, in such a conventional facsimile device, the controller of the facsimile device controls the radio unit by a radio system inherent in the controller. For this reason, the controller cannot control another type of radio unit.
More specifically, a radio unit cannot be shared by this facsimile device and another facsimile device, and radio units must be formed for the types of facsimile devices, respectively.
In a facsimile device in which radio communication between a transmitter/receiver and the facsimile device is established, when the transmitter/receiver receives an incoming notification to respond to the incoming notification, and the facsimile device performs an automatic receiving operation, a radio line between the transmitter/receiver and the facsimile device is suddenly cut off, or no notification is transmitted from the facsimile device to the transmitter/receiver even if the radio line is not cut off. For this reason, an operator who answers the notification with the transmitter/receiver suddenly hears noise.
When communication between the transmitter/receiver and the facsimile device cannot be established, since an alarm tone is output by an alarm unit built in the transmitter/receiver, a signal from the facsimile device can be received by the transmitter/receiver. However, when the facsimile device cannot receive a signal from the transmitter/receiver, the transmitter/receiver cannot recognize that communication with the facsimile device cannot be established, and the transmitter/receiver cannot make an alarm tone indicating disable communication.
It is an object of the present invention that a radio unit, included in a communication device, for performing radio communication can be replaced with another type of radio unit.
It is another object of the present invention that an interface for exchanging a control signal between a radio unit for performing radio communication and a communication device performing communication through a communication line is shared by different types of radio units.
It is still another object of the present invention that a control signal exchanged between a radio unit for performing radio communication and a communication device performing communication through a communication line is shared among different types of radio units.
It is still another object of the present invention that when communication using a radio unit is switched to communication without a radio unit, the radio unit notifies a communication device which is performing radio communication that the communications are switched.
Still another object of the present invention will be apparent from the following specification and drawings.